Despite advances in early detection and standard treatment, non small cell lung cancer (NSCLC) and hepatocellular carcinoma (HCC), are often diagnosed at an advanced stage and have poor prognoses. Promoting apoptosis is a possible goal for drug development. TNF-related apoptosis-inducing ligand (TRAIL) is currently being tested in clinical trials; however the resistance of many tumors, including NSCLC and HCC, to TRAIL represent obstacles to its clinical application.
miRNAs are small non-coding RNAs of 19-25 nt that can block mRNA translation and/or negatively regulate its stability. At this time, over 500 different miRNAs have been identified in human cells and evidence indicates that regulation of miRNA levels is associated with growth and differentiation of many cell types and tissues. Dysregulated miRNA expression has been associated with solid and hematopoietic malignancies, and there is evidence that some miRNAs may function as oncogenes or tumor suppressor genes. miR-221 and miR-222 are among the most deregulated miRNAs implicated in cancer. Their expression is highly upregulated in a variety of solid tumors, including thyroid cancer, hepatocarcinoma and melanoma cells. Elevated miR-221 and miR-222 expression has been causally linked to proliferation, apoptosis, and migration of several cancer cell lines. However, the molecular mechanisms mediating miR-221 and miR-222 function in cancer generally, and in NSCLC and HCC specifically, is largely unknown prior to the present invention.
PTEN is a tumor suppressor in human cancers and a regulator of cell growth and apoptosis. Functionally, PTEN converts phosphatidylinositol-3,4,5-trisphosphate (PIP3) in the cytoplasm to phosphatidylinositol-4,5-bisphosphate (PIP2), thereby directly antagonizing the activity of PI3 kinase (PI3K). PTEN inactivation results in constitutive activation of the PI3K/AKT pathway and in subsequent increase in protein synthesis, cell cycle progression, migration and survival. In addition, various studies have demonstrated that the protein phosphatase activity of PTEN inhibits activation of mitogen-activated protein kinase (MAPK) via several pathways. PTEN is associated with the development of multiple drug resistance, including that to TRAIL. Constitutive activation of AKT contributes to cell migration and invasion in different types of tumors, including lung and liver carcinoma.
TIMP3 is a member of a group of proteins called matrix metalloproteinases (MMPs). MMPs are a family of zinc proteases involved in the breakdown of extracellular matrix (ECM) in normal physiological processes, such as embryonic development, tissue and bone remodeling, wound healing, and angiogenesis. Within the extracellular matrix, the tissue inhibitors of metalloproteinases (TIMPs), of which there are four family members (TIMP1 through 4), inhibit the activity of MMPs by binding with a 1:1 stoichiometry to the active site. Over-expression of TIMP3 in vascular smooth muscle cells and melanoma cell lines inhibits invasion and promotes apoptotic cell death. TIMP3, has been reported to induce the activation of both initiator caspases-8 and -9. TIMP3 has been associated with angiogenesis and tumor formation.
MET, also known as c-Met, is a membrane receptor for the hepatocyte growth factor (HGF)/scatter factor (SF). MET is normally expressed by cells of epithelial origin, while expression of HGF is restricted to cells of mesenchymal origin. Upon HGF stimulation, MET stimulates the invasive growth of cancer cells and increases their metastatic potential, principally through increased phosphorylation of ERK1/2 and JNK.
Phosphorylated JNKs activate the oncoprotein, c-Jun, which is known to form the activator protein-1 (AP-1) transcription factor as a homodimer or heterodimer with its partner c-Fos. Aberrant expression of HGF/SF and its receptor, MET, often correlates with poor prognosis in a variety of human malignancies. Due to their specific toxicity for malignant cells, recombinant forms of TRAIL are apoptosis-based anti-tumor agents. However, many human cancer cells remain resistant to TRAIL-induced apoptosis, but the mechanism of such resistance is not clear.